PERICOM SEMICONDUCTOR CORP.

PERICOM SEMICONDUCTOR CORP. Patent applications

Patent application number

Title

Published

20130049765

In-Situ Cable Unplug Detector Operating During Normal Signaling Mode - An in-situ unplug detector circuit detects when a cable is disconnected or unplugged. Detection does not have to wait for normal signaling to pause, such at the end of a frame or timeout. Instead, detection occurs during normal signaling. When the cable is disconnected, the transmitter no longer drives the load at the far end of the cable, and thus can drive the near end to a higher high voltage and to a lower low voltage. The increased voltage swing is detected by a detector at the near end that amplifies the transmitter output to the cable. A fast detector has a higher bandwidth and faster response time than a slow detector, and generates a fast detect signal that crosses over a slow detect signal. When the cable is disconnected, the fast detect signal again crosses over the slow detect signal, and decision logic activates an unplug signal.

02-28-2013

20120242377

Re-Driver with Pre-Emphasis Injected Through a Transformer and Tuned by an L-C Tank - A re-driver circuit has pre-driver, intermediate, and output stages. Pre-emphasis on the output is generated by the intermediate stage and injected into an output stage. The intermediate stage is a frequency-tuned amplifier that has an inductive-capacitive L-C tank circuit that is tuned to a desired frequency of the output. The intermediate stage does not directly drive the output stage. Instead, an on-chip coupling transformer couples the L-C tank circuit to the output stage. The coupling transformer has a first inductor that is part of the L-C tank circuit in the intermediate stage, and a second inductor that is part of the output stage. Mutual inductance between the first inductor and the second inductor inductively couple a pre-emphasis voltage onto the output. The magnitude of the pre-emphasis can be changed by adjusting current in the intermediate stage.

09-27-2012

20120235704

Redriver with Output Receiver Detection that Mirrors Detected Termination on Output to Input - A redriver chip is inserted between a transmitter chip and a receiver chip and re-drives differential signals from the transmitter chip to the receiver chip. The redriver chip has switched output termination that switches to a high value to detect far-end termination at the receiver chip, and to a low value for signaling. An output detector detects when the receiver chip has termination to ground and enables switched input termination to provide termination to ground on the lines back to the transmitter chip so that the far-end termination on the receiver chip is mirrored back to the transmitter chip, hiding the redriver chip. An input signal detector detects when the transmitter chip begins signaling and enables an equalizer, limiter, pre-driver, and output stage to re-drive the signals to the receiver chip. The input signal detector also causes the switched output termination to switch to the low value termination for signaling.

09-20-2012

20120087405

Trace Canceller with Equalizer Adjusted for Trace Length Driving Variable-Gain Amplifier with Automatic Gain Control Loop - Distortions of both amplitude and phase along a transmission line are compensated for by a trace canceller inserted between a transmitter and a receiver. The trace canceller has an equalizer that compensates for a trace length between the transmitter and the trace canceller. A variable gain amplifier between the equalizer and an output buffer has its gain controlled by an automatic gain control circuit that compares low-frequency swings of the input and output of the trace canceller. The gain of the variable gain amplifier is reduced to prevent the output buffer from saturating and clipping peak voltages on its output. Thus both the variable gain amplifier and the output buffer remain in the linear region. Training pulses from the transmitter are passed through the trace canceller without clipping of peak voltages, allowing the transmitter and receiver to adjust transmission parameters to best match the transmission line.

04-12-2012

20100308899

Dual-Output Triple-Vdd Charge Pump - A dual-output triple-Vdd charge pump as two pumped outputs that are both pumped to three times the power-supply voltage, 3×Vdd. This pumped output voltage is reduced by two p-channel inner diode drops, to 3×Vdd−2×|Vtp|. A pair of cross-coupled n-channel transistors alternately charge two inner nodes from the power supply. Inner pumping capacitors drive inner nodes between Vdd and 2×Vdd, and the cross-coupling of the gates turns off one of the cross-coupled n-channel transistors when its inner node is being driven high. A p-channel inner diode transistor connects an inner node to an outer node, causing a |Vtp| drop. The outer node is also pumped by an outer pumping capacitor that drives the outer node between 2×Vdd−|Vtp| and 3×Vdd−|Vtp|. A p-channel outer diode transistor conducts from the outer node to the pumped output node, causing another |Vtp| voltage drop. The pumped output voltage is maintained at 3×Vdd−2×|Vtp| by an output capacitor.

12-09-2010

20100127734

Out-Of-Band Signaling Using Detector with Equalizer, Multiplier and Comparator - Power-down mode is activated when equal voltages are detected on a pair of differential inputs. The voltage difference across the differential inputs is equalized by an equalizer and then applied to a multiplier and smoothed and filtered by a low-pass filter to produce an average signal. The average signal is compared to a reference voltage to detect when the voltage difference across the differential inputs is too small. A power-down signal is activated when the average signal is too small. The reference voltage compared can be generated by an equalizer, multiplier, and low-pass filter to match process, temperature, and supply-voltage variations in the primary signal path. The multipliers can be implemented with Gilbert cells. The equalizers can receive control signals to control attenuation of different frequency components.

05-27-2010

20100105319

Redriver with Output Receiver Detection that Mirrors Detected Termination on Output to Input - A redriver chip is inserted between a transmitter chip and a receiver chip and re-drives differential signals from the transmitter chip to the receiver chip. The redriver chip has switched output termination that switches to a high value to detect far-end termination at the receiver chip, and to a low value for signaling. An output detector detects when the receiver chip has termination to ground and enables switched input termination to provide termination to ground on the lines back to the transmitter chip so that the far-end termination on the receiver chip is mirrored back to the transmitter chip, hiding the redriver chip. An input signal detector detects when the transmitter chip begins signaling and enables an equalizer, limiter, pre-driver, and output stage to re-drive the signals to the receiver chip. The input signal detector also causes the switched output termination to switch to the low value termination for signaling.